I believe such wider "tracks" on the ball could also be achieved by the ball pitching and yawing during its travel down the barrel. Many have taken it as a given that the ball will face some rotation when fired - if the ball does in fact distort to this semi-cylindrical shape, such rotation would not be possible. Thus "hook" shots caused by a yawing spin couldn't happen.

Bill,
If you do the test as I described for yourself, you will see that the tracks or skid marks on the ball are to consistent to be made by a ball that is merely bouncing through the barrel as a result of yaw and pitch. If the ball did not seal to the bore and be held relatively straight, air blowing past the ball on one side would generate a great deal of spin as the other side would be slowed down by its contact with the bore. The same prinicple that generates the spin on the ball that goes through the curved and very large bore barrel of the Tippmann flatline barrel. The curve of the barrel forces the ball against the wall of the tube, creating friction while propulsion air can blow past the ball on the other side to amplify the spin. The biggest drawbact that I see in spinning a paintball is the fact that they are not round and feeding does not allow for the ball to be fed into the chamber with the seem of the ball in the same orientation to the axis of the barrel with each shot. By breach loading a paintgun to place each ball in the chamber with its seem in a controlled orientation to the barrel it is fairly easy to see how the flight of the ball is affected by the orientation of the seem when it is fired. When the seem of the ball is against the full perimeter of the bore; muzzle velocity is just a bit higher and the hits on target will be pretty much in the same group but with a somewhat vertical spread. When the ball is loaded so the seem is placed lineal to the axis of the bore, (starting with a 12 oclock and 6 oclock orientation) the center of the shot group will be in a different location on the target and show a more horizontal spread. Loading with the seem orientation changed on either axis creates shot groups in a clock-like pattern on target. Also noted in these same tests was that the less spin seen on the ball in flight, the tighter the shot groups; regardless of the orientation of the seem. Velocity and muzzle blast also plays a big role in the size of the shot groups.
It is important to note here that the first of the above tests was done with a known gun with an 11" barrel and precisely tuned valving but ran the same tests with a test bed unit in order to see the results of varying barrel and valve configurations.

Quote:

Originally posted by billmi

I've had a look at some of the high speed video and stills Tom has taken of balls fired through a clear barrel (some is included in the Automag RT video.) If the balls are distorting, it is too insignificant to see in the photographs. An important question to which I hope Tom can supply an answer is, where those done with gelatin paintballs, or with Perfect Circle paintballs, which have a more rigid plastic shell?

I'm not saying that the ball flattens out like a pancake; it simply can't do that within the confines of the barrel. However, it dosn't take much "distortion" to make a big difference in how the ball acts when it is fired. Just as it takes only one small speck of paint, in an otherwise pristine barrel, to send a ball off into never-never land when shot.
What I am saying, is that we need the ball to upset somewhat so that it can seal against the bore and achieve maximum potential from the internal balistics. However, we also need for the internal balistics to cease acting on the ball before it leaves the barrel if we are to expect any kind of consistency from a relatively innconsistent projectile.
Also, (in keeping with the thread) closed bolt firing seems to give me the best opportunity to to dial in my equipment and make the most out of every ball shot.

Quote:

Originally posted by billmi

Please also note, I will happily disagree with Glenn on theory or interpretation of the results of a test or experiment, but this in no way means I don't respect his viewpoint. There are a lot of people in the industry that will support a certain theory regardless of its validity, simply as a means to market their product. Basically they have a product, and whip up a theory to explain to you why it's the best in the world and you need to buy it. Glenn on the other hand, has used his theories of paintgun operation to build quality products, and is one of the few manufacturers/customizers to understand the concepts of old world craftsmanship.

See you on the field,
-Bill Mills

Thanks for your support Bill. I am about as old school and old fashioned as they come. I just can't operate on theory or conjecture besides having a starting point in the search for actual improvement. The bulk of what I know about paintball equipment and shooting paintballs has come from a great deal of trial and error and/or trial and success that has been focused only on how to get my own equipment to allow me to play my best game. When common sense thinking leads to a success a process will become a standard part of what we do and I will gladly share the results with others. I have also learned a great deal from my errors as well. :rolleyes:
Sometimes it gets difficult to share something without it looking like a marketing ploy and many just do not understand that, that just is not my style. You know my views on common marketing practices because we have discussed it on a personal basis.

11-16-2002, 04:41 PM

Paladin

Quote:

Originally posted by billmi

Glenn,

In a previous post you said the open/closed bolt accuracy test did not show a difference between bolt position because the test gun was not tuned for optimal closed bolt performance.

Would it not be a possibility that it's the tuning that is optimizing efficiency and consistency in the gun setup, rather than bolt position that has provided the improved performance in your experiences?

Se you on the field,
-Bill Mills

Yes indeed, the tuning makes a huge difference. As I see it, closed bolt operation gives me a better opportunity to tune the shot effectively. I must reiterate here that my stand on closed bolt operation is based on a comparison with a open-bolt firing system that uses the same blast of air to both launch the projectile and cycle the action reward in preparation for the next shot. ie: a blow-back operated system like the Stingray and numerous others . (in my opinion, the valving for a Stingray leaves much to be desired regardless of how it is to be used. I've just not been able to get real good results from the Crossman style inline valve used in the Stingray)
Although, awhile back I had the opportunity to convert a Spyder from blow-back operation to closed bolt firing with our pneumatic automation system and the improvement to overall performance was quite noticeable even with the only change to the valve being a valve stem that did not allow flow to the rear for blow-back cocking. Better efficiency, better consistency and a much tighter shot grouping were immediately evident. The improvement in performance may have only been the result of seperating the feeding action from the firing action. This allows the hammer to strike the valve more consistently because it doesn't have to overcome variables in ball size and positioning when feeding and it doesn't have to deal with the drag related to the o-ring on the front of the hammer. I also believe that giving the propulsion gas a solid wall to push against instead of having an amount of the same blast of air drawn off to the rear to blow the action back, aids considerably in achieving optimum effectiveness from the shot.

If my typing wasn't so damned slow, this would be a great deal easier.:)

11-16-2002, 11:55 PM

AGD

Quote:

Originally posted by pbjosh AGD-

That is a given. The balls spin when they leave the gun. All of them do.
Spin is the entire issue for accuracy and range.

Josh, this is a very broad statement. Yes the Magnus effect is real but you have not proved that a paintball spins with every shot and that this has an all encompasing effect on accuracy. I could say with just as much confidence that the ball never spins, and all the inaccuracy is due to wind currents throughout the balls flight path which buffet it off course.

Glen,

It's dangerous to look at the ball scuff marks and deduce what's happening in the barrel. A much better approach is to lightly powder the barrel, shoot one shot and inspect the bore.

AGD

11-17-2002, 12:02 AM

Blazestorm

Why does Tom get to be the smart one... I wish I was smart :(

11-17-2002, 12:50 AM

Paladin

Quote:

Originally posted by AGD

Glen,

It's dangerous to look at the ball scuff marks and deduce what's happening in the barrel. A much better approach is to lightly powder the barrel, shoot one shot and inspect the bore.

AGD

Not so dangerous if you wait until the ball ends it flight before inspecting it closely.:D

Since I know there is generally more than one way to "skin a cat", I'll give the powder method another try or ten when I get to the shop on Monday and see what that tells me.
However, I don't have a good bore scope that would allow me as close a look as I would like.

11-17-2002, 07:55 AM

pbjosh

AGD-

I have been around for a little while, and I know only being here in the sport for 12 years next spring makes me seem like a lightweight compared to Yourself, Glenn and Bill.

But it would be hard for me to look back at a couple solid years of play and remember a time, while shooting two tone paint, that I DIDN'T see it spin.

Prove to me that my Eye's are wrong, and that the ball is NOT spinning, ever.

As for blaming the wind, I have shot paint out a moving vehicle. Quite often in the past. And in heavy wind. And we have had some serious wind in Alaska.

If what your saying, that the ball doesn't spin, that it is only wind affects- I am sorry, I would need THAT to be proven. These are balls, they are moving through the air at 200mph. Inherent spin would affect them more then light random air currents. A gun that shoots lousy will still shot lousy on a perfectly calm day. The gun is causing something to go wrong. It is causing spin. Another gun, accurate as hell, will still shoot straight on a slightly windy day. Because two guns shoot differently in the same wind conditions. That alone would make the "and all the inaccuracy is due to wind currents throughout the balls flight path which buffet it off course. " statement incorrect. The problem is something that happens before the ball can even hit the "wind currents". If that was true, barrels would have NO affect on paint, different guns would all shoot the same on a given day.

Since what you are saying is that the gun doesn't affect the accuracy at all, all the gun, barrels, shoot exactly the same on any given day- Because of wind currents-

I can prove that wrong.

Josh

11-17-2002, 09:12 PM

flanders

ok well i just did a huge *** project for cience testing just this, open vs closed bot, i used my tricked micro cocker and a buddy's dark angel

what i found was that over all at the range i did (25 yards) both guns are pretty dman accurate, although over all my cocker was slightly better not by much if u want more detail im me

11-17-2002, 10:13 PM

ezrunner

results?

can you post results, including:

paint used,
barrel(s) used
and any wind or temp info you
had?

-rob

11-17-2002, 11:33 PM

kilaueakid

Is it possible that the ball starts to spin as it is being pushed past the detent/s from friction, and when the air blast hits it, it increases the speed of the spin. As each ball size differs, this friction could differ or not exist, thus making a ball occasionally move left to right, or up/ down depending on what type of friction. There could also be some type of rolling action happening while the ball is dropping into the breach??

kila

11-18-2002, 03:37 AM

AGD

Josh,

I am not saying that the wind currents affect the ball. I am using that as an analogy to compare it to what you are saying.

Against my better judgement I am going to post some of my actual testing data here in the forum. I want to see if you all take the time to really analize it and come to some conclusions. I am afraid in doing this that everyone will just use the info to argue their own side instead of really trying to understand what's happening.

Maybe its the right time now that we have a bunch of "on the ball" people here in this forum. I am going to close this thread in order to start another one thats more on target with the discussion at hand. Lets move over there. I will put the data up in the data thread and then you can copy it down to the new thread for discussion.